A liquid crystal display panel includes multiple pixel units arranged in an array. Each pixel unit includes three sub-pixels which are red, green, and blue. A pixel electrode in each sub-pixel is connected to a Gamma voltage, which is used to control a display gray scale (i.e., brightness) of the sub-pixel. Voltage differences between Different Gamma voltages and common electrode voltages cause liquid crystal molecules to rotate differently, which in turn generates differences in the light transmissivities, thereby achieving the display of gray scale.
A Gamma voltage determination method comprises fitting a desired Gamma curve (i.e., an ideal Gamma curve) through a gray scale-light transmissivity curve of the liquid crystal display panel, and then calculating Gamma voltages corresponding to various gray scales according to the ideal Gamma curve and a Voltage-Light Transmissivity (V-T) curve of the liquid crystal display panel.
The Gamma voltages need to be generated by a corresponding Gamma voltage generation circuit. At present, the Gamma voltage generation circuit generally generates the Gamma voltages by way of voltage division with resistors in series, and resistances of resistors inside the circuit are calculated according to the determined Gamma voltages. Taking a 6-bit binary coded data driver as an example, a process of changing from all-white to all-black may be divided into 26=64 gray scales, and it needs to generate 64 Gamma voltages. As shown in FIG. 1, a Gamma voltage generation circuit inside the data driver includes totally 63 resistors R0˜R62 connected successively in series, which generates 64 Gamma voltages V0˜V63, where V0, V1, V15, V31, V47, V62 and V63 are provided respectively in turn by external voltages Vr1˜Vr7, and all remaining voltages need to be generated by voltage division with resistors.
However, it is found in a practical application process that an original Gamma voltage generation circuit will cause a deviation between the actual Gamma curve and the ideal Gamma curve, when the V-T curve of the liquid crystal display panel changes. Therefore, there is a need to redesign and modify the Gamma voltage generation circuit, which results in an extended production cycle (which typically is one month), considerably degrading the production efficiency.